Relay



Patented Aug. 29, 1939 UNITED STATES PATENT OFFICE RELAY Jacob R. Fry,Telephone Montclair, N. J., assignor to Bell Laboratories, Incorporated,New

4 Claims.

This invention relates to relays and more particularly to relays for usein the circuits of telephone systems.

In electric circuits and particularly in telephone circuits, largenumbers of electromagnetic relays are employed for performing numerousand varied circuit switching functions. It is often very essential thatrelays employed in such circuits shall positively make and break thecircuits controlled over their contacts. If the contacts of a relay donot make firmly or break cleanly, or in other words, if the contactshave a tendency to chatter when they make or break, false operation inthe circuits controlled thereover will result.

It has been found that one of the factors which contributes to thetendency of relay contacts to chatter upon the release of the relayarmature, is the bouncing or rebound of the armature from the back stopstructure which is employed to limit the releasing movement of thearmature and to adjust the normal air-gap between the relay armature andthe pole-face of the core. It has further been determined throughexperimentation that the rebound of the armature from the back stopstructure may be materially reduced and the consequent chattering of therelay contacts controlled by the armature substantially eliminated bythe provision of means for absorbing the shock of impact of the armaturewithin the back stop structure.

It is therefore the object of this invention to improve the design ofthe back stop structure of an electromagnetic relay so as to reduce thearmature rebound and to consequently eliminate contact chatter. Thisobject is attained in accordance with the present invention by theprovision of an insert in the face of the back stop nut with which therelay armature engages upon its releasing movement and which, due to itsfrictional engagement Within the body of the nut, absorbs the energy ofimpact.

Specifically, the back stop nut is provided with a recess in its facewithin which an insert of smaller diameter and less depth than therecess is retained by swaging the lower rim of the recessed portion, orby the application of a retaining ring to the lower face of the nut. Theouter face of the insert projects beyond the outer face of the nut forengagement with the relay armature and the edge of the inner face of theinsert is rounded oil to make a sliding engagement with the inner covedWall of the recess whereby, when the outer face of the insert is engagedby the relay armature, the insert is pushed into the recess with alateral sliding movement. The friction produced by the sliding andinward movement of the insert is sufficient to materially absorb theenergy of impact of the armature therewith thereby reducing the tendencyof the armature to rebound from the stop nut. When the armature hascompleted its travel toward the stop nut, the insert rests with itsinner face against the bottom of the recess and thus limits the furtherreleasing travel of the armature.

icidentally, when the armature is again attracted away from the stopnut, the insert is free to follow the armature from its position of restand the armature readily breaks away from the insert under any tendencyof the armature to stick to the outer face of the insert and thus anyretarding action in the operation of contacts controlled thereby iseliminated.

The invention will be more readily understood from the followingdetailed description taken in connection with the accompanying drawingin which:

Fig. 1 is a side elevational View of a well-known type of relay to whichthe invention has been applied;

Fig. 2 is an enlarged side elevational view of the stop nut constructedin accordance with the invention;

Fig. 3 is a cross-sectional view of the stop nut disclosed in Fig. 2;and

Fig. 4 is a cross-sectional view of a stop nut showing an alternativemode of construction.

The relay disclosed in Fig. 1 of the drawing is of a well-known typeconsisting of a core I secured at its rear end to a mounting bracket 2,an energizing coil 3 surrounding the core I, an armature 4, the forwardend of which cooperates with the pole-face 5 of the core I and the rearend of which is pivoted by pivot pins on ledge 6, coil terminal lugs 7and a spring pile-up on each side of the relay coil 3, each comprisingsuitable contact springs such as 8 and 9. The ledges 6, coil terminallugs l and springs 8 and 9 of each spring pile-up are suitably clampedto the mounting bracket 2 by screws I0 and II which pass through theclamping plate I2, insulating strips I 3, the ledges t, the bracket 2,insulating strips I4 and the springs 8 and 9 into threaded holes in theclamping plate I5. The terminal lugs 1 and springs 8 and 9 are insulatedfrom each other and from the bracket 2 by the interposed insulatingstrips I3 and H. For engaging the contacts of springs 8 and 9 upon theattraction of the armature 4 to the core I, the armature is providedwith operating studs material.

To limit the movement of the armature 4 away from the core I upon thedeenergization of the coil 3 and to afford means for adjusting thenormal air-gap between the end of the armature 4 and the pole-face 5 ofthe core I, the back stop screw 51 carrying the back stop nut I 8 isprovided. The back stop screw I1 is L-shaped having its vertical armthreaded to receive the back stop I6 of insulating nut l8 and having itshorizontal arm seated in a hole in the end of the core I.

The back stop. nut 18 comprises a body l9 having a hub portion 20internally threaded and provided with a slot 2i whereby the twoportionsof the hub portion 20, thus formed, may be insure that when thenut upon the threaded end of IT to adjust the air-gap pole-face 5pinched together to has been threaded the back stop screw between thearmature 4 and the of the core I, as disclosed in Fig. 1, the adjustmentwill be maintained. Formed centrally in the lower face of the nut is arecess 22 having a coved corner 23 between its bottom wall 24 and itscylindrical wall 25.

Positioned within the recess 22 is an insert 26 having a hub portion 21extending beyond the lower face 28 of the body of the nut and providedwith an axial opening 29 of sufficient diameter .to freely admit theback stop screw I! therethrough and to permit lateral movement of theinsert 26 within the recess 22 of the nut. The inner edge of the insertformed by the junction of the inner face as and the cylindrical wall 3!thereof, is rounded off as disclosed at 32, for engagement with thecoved corner 23 of the recess for a purpose to be later described.

To retain the insert within the recess of the nut, the lower face of thebody of the nut may be swaged as shown in Fig. 3, to form an inwardlyextending lip 33, or a retaining ring 34 may be brazed or otherwisesecured to the lower face of the nut, as shown. in Fig. 4.

With the back stop nut l8 assembled upon the screw ll and adjusted tothe position requisite for limiting the releasing travel of the relayarmature 4 to a position in which the required air-gap between thearmature and the pole-face 5 of the core is attained, as disclosed inFig. 1, when the armature is attracted to the core by the energizationof the operating coil 3, the insert 26 will assume the position withinthe recess 22 of the nut as disclosed in Fig. 3. When thereafter theenergizing coil 3 is deenergized to release the armature 4, the armatureunder the influence of the springs 8 and 9 will travel toward and intoengagement with the face of the hub 2! of the insert 26 forcing itinwardly into the recess 22 in the body 19 of the nut. As the insertmoves inwardly, the engagement of its rounded edge 32 with the covedcorner 23 of the recess will cause it to also move laterally within therecess until its inner face 33 abuts the bottom wall 24 of the recess.When this occurs the release travel of the armature 4 is arrested in theposition in which the required airgap between it and the pole-face 5 ofthe core is attained.

Due to the sliding and frictional engagement between the cylindricalwall and rounded corner of the insert and the cylindrical wall and covedcorner of the recess, the energy of the impact incident to the armaturestriking the hub 2'! of the insert is largely dissipated and thetendency of the armature to rebound from the stop nut is thereby reducedand, since the armature controls the engagement between. the contactsprings 8 and 9 of the spring pile-ups through the studs 16 carried bythe armature, the tendency of the armature to impart such vibrationincident to its impact with the stop nut to the contact springs as tocause them to chatter is materially reduced.

The insert 26 being loosely supported within the body of the nut I8 isalso effective in overcoming the sticking of the armature 4 to the backstop nut when the armature is attracted toward the core 5 since theinsert will follow the travel of the armature until it is arrested byits engagement with the retaining lip 33 or ring 34 and thereafter, thearmature will easily break away from the outer face of the hub portion21 of the insert. The outer face of the hub portion 21 being of smallarea and the insert having a tendency to slightly vibrate due to themovement of the armature in its releasing motion, the suction which mayexist between the face of the hub portion and the surface of thearmature due to sticky deposits thereon or due to the fact that suchsurfaces are worn smooth will be so reduced that no appreciable delay inthe attraction of the armature toward the core and the consequentoperation of the relay contacts will result.

What is claimed is:

1. In an electromagnetic structure having a core and an armaturecooperating therewith, a back stop for adjusting the air-gap betweensaid armature and said core comprising a screw and a nut thereon, saidnut having a cylindrical recess therein, the junction between the bottomand cylindrical walls of which is coved, and a cylindrical captiveinsert in said recess with which said armature engages having thejunction between its inner face and cylindrical wall rounded off forsliding engagement with the coved portion of said recess.

2. In an electromagnetic structure having a core and an armaturecooperating therewith, a back stop for adjusting the air-gap betweensaid armature and said core comprising a screw and a nut thereon, saidnut having a cylindrical recess therein, the junction between the bottomand cylindrical walls of which is coved, and a cylindrical captiveinsert in said recess with which said armature engages, the junctionbetween the inner face and cylindrical wall of which is rounded forproducing in conjunction with the coved portion of said recess a lateralmovement of said insert within said recess, and said insert having acentral opening therein through which said screw passes of sufficientdiameter to permit the lateral movement of said insert.

3. In an electromagnetic structure having a core and an armaturecooperating therewith, a back stop for adjusting the air-gap betweensaid armature and said core comprising a screw and a nut thereon, saidnut having a recess therein, an insert movable inwardly and laterallywithin said recess, and a ring secured to the outer face of said nut forretaining said insert within said recess.

4. In an electromagnetic structure having a core and an armaturecooperating therewith, a back stop for adjusting the air-gap between thearmature and said core comprising a screw and a nut adjustable thereon,said nut having a recess therein provided with a constricted openingthrough the face of said nut and a plug having a head portion largerthan said constricted opening movably positioned in said recess andhaving a shank extending through said opening with which said armatureengages when said armature is released to its normal position, said plughaving a central opening therethrough through which said screw passes ofsufiicient diameter to permit lateral movement of said plug within saidrecess.

JACOB R. FRY.

